Mono.CSharp.OptionalAssign.DoResolve C# (CSharp) Method

        protected override Expression DoResolve(ResolveContext ec)
        {
            CloneContext cc = new CloneContext ();
            Expression clone = source.Clone (cc);

            clone = clone.Resolve (ec);
            if (clone == null)
                return null;

            //
            // A useful feature for the REPL: if we can resolve the expression
            // as a type, Describe the type;
            //
            if (ec.Module.Evaluator.DescribeTypeExpressions){
                var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
                Expression tclone;
                try {
                    tclone = source.Clone (cc);
                    tclone = tclone.Resolve (ec, ResolveFlags.Type);
                    if (ec.Report.Errors > 0)
                        tclone = null;
                } finally {
                    ec.Report.SetPrinter (old_printer);
                }

                if (tclone != null) {
                    Arguments args = new Arguments (1);
                    args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
                    return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
                }
            }

            // This means its really a statement.
            if (clone.Type == TypeManager.void_type || clone is DynamicInvocation || clone is Assign) {
                return clone;
            }

            source = clone;
            return base.DoResolve (ec);
        }